Internal intermediate pressure multistage compression type rotary compressor, manufacturing method thereof and displacement ratio setting method

ABSTRACT

There is provided an internal intermediate pressure multistage compression type rotary compressor capable of reducing a height dimension while reducing the amount of oil to be discharged outside. An electric element and first and second rotary compression elements which are driven by a rotary shaft of the electric element disposed under the electric element are provided in a hermetic shell case. There is provided a refrigerant introduction pipe for introducing refrigerant in the hermetic shell case over the electric element into the second rotary compression element through an outside of the hermetic shell case. There is provided an oil path provided in the rotary shaft for discharging oil through an oil discharge port which is positioned at the upper end of the rotary shaft. The refrigerant introduction pipe is provided such that apart of an inlet of the refrigerant introduction pipe is positioned under the upper end of a stator of the electric element.

FIELD OF THE INVENTION

The invention relates to an internal intermediate pressure typemultistage rotary compressor comprising an electric element in ahermetic shell case, and first and second rotary compression elementsbeing positioned under the electric element and driven by a rotary shaftof the electric element, wherein refrigerant compressed and dischargedby said first rotary compression element is discharged into the hermeticshell case, and the thus discharged intermediate pressure refrigerant issucked in and compressed by the second rotary compression element anddischarged into hermetic shell case, and a method of manufacturingmethod the internal intermediate pressure multistage compression typerotary compressor and a method of setting displacement ratio thereof.

BACKGROUND OF THE INVENTION

A conventional internal intermediate pressure type multistage rotarycompressor of this type is, for example, disclosed in Japanese Laid-OpenPublication No. 2-294587 (F04C23/00). Such a rotary compressor isprovided with an electric element in a hermetic shell case and a rotarycompression mechanism which is positioned under the electric element andcomprises first and second rotary compression elements which are drivenby a rotary shaft of the electric element. When the electric element isactuated to rotate the rotary shaft, refrigerant is sucked into a lowpressure chamber of a cylinder through a suction port of the firstrotary compression element (first stage) provided under the electricelement, and the refrigerant is subjected to compression of first stageby the operation of the roller and a vane and is changed intointermediate pressure refrigerant, which is in turn discharged from ahigh pressure chamber of a cylinder into the hermetic shell case underthe electric element through a discharge port, a noise eliminatingchamber, and an intermediate discharge pipe.

Oil is separated from the intermediate pressure refrigerant dischargedinto the hermetic shell case, and the refrigerant flows into arefrigerant introduction pipe provided under the electric element, andpasses through the outside of the electric element, then is sucked intothe low pressure chamber of a cylinder 238 through a suction port 261 ofthe second rotary compression element 234 (second stage) as shown in theleft side of FIG. 22, wherein it is subjected to compression of secondstage by the operation of the roller 246 and the vane 250, which is inturn changed into high temperature high pressure refrigerant. The hightemperature high pressure refrigerant passes through a discharge port239, a noise eliminating chamber, and is discharged into a refrigerationcircuit through the outside of the refrigerant discharge pipe. A cycleof the thus discharged refrigerant is repeated such that the dischargedrefrigerant flows into a radiator (gas cooler) and the like of therefrigeration circuit, and radiates heats, then it is throttled by anexpansion valve and heat thereof is absorbed by an evaporator, and itreturns to the first rotary compression element through the refrigerantintroduction pipe and is sucked in the first rotary compression element.

In this case, displacement of the second rotary compression element isnormally set to be smaller than that of the first rotary compressionelement.

An oil path is provided in the rotary shaft of such a rotary compressor,and oil stored in the oil reservoir provided at the bottom of thehermetic shell case is pumped up in the oil path by an oil pump (supplymeans) attached to the lower end of the rotary shaft. The thus pumped upoil is supplied to the rotary shaft and the sliding portions andbearings of the first and second rotary compression elements so as tolubricate therein and seal them, and it is discharged through an oildischarge port provided at the upper end of the rotary shaft so as tocool the electric element in the hermetic shell case and lubricatevarious sliding portions at the periphery thereof.

In the internal intermediate pressure multistage compression type rotarycompressor, the refrigerant compressed by the second rotary compressionelement is discharged outside as it is. However, the foregoing oil whichis supplied to the sliding portions of the second rotary compressionelement is mixed in the refrigerant, and hence the oil is dischargedtogether with the refrigerant. Accordingly, there arises a problem thata large amount of oil flows in refrigeration circuit of therefrigerating cycle, thereby deteriorating the performance ofrefrigerating cycle.

Further, with such a rotary compressor, since a pressure (high pressure)in the cylinder of the second rotary compression element is higher thana pressure (intermediate pressure) in the hermetic shell case having thebottom serving as the oil reservoir, it is difficult to supply oil tothe second rotary compression element utilizing the difference in thesepressures.

Therefore, it is contemplated that the intermediate pressure refrigerantdischarged from the first rotary compression element is not dischargedinto the hermetic shell case, but the high pressure refrigerantdischarged from the second rotary compression element is discharged intothe hermetic shell case, thereby rendering the interior of the hermeticshell case to be high pressurized. That is, with such an internal highpressure multistage compression type rotary compressor, the refrigerantis sucked through the suction port of the first rotary compressionelement in the low pressure chamber of the cylinder, and it is subjectedto compression by the operation of the roller and the vane and ischanged into the intermediate pressure, which is in turn discharged fromthe high pressure chamber of the cylinder into the discharge port andthe noise eliminating chamber. The refrigerant discharged into the noiseeliminating chamber passes through the refrigerant introduction pipe,and it is sucked in the low pressure chamber of the cylinder through thesuction port of the second rotary compression element, then it issubjected to compression of second stage by the operation of the rollerand vane and is changed into a high temperature high pressurerefrigerant, which is in turn discharged from the high pressure chamberinto the hermetic shell case through the suction port and the noiseeliminating chamber.

Although it is configured that the high pressure refrigerant in thehermetic shell case flows into a radiator through the refrigerantdischarge pipe, it is expected that the amount of oil to flow outsidecan be reduced and the supply of oil to the sliding portions can beeasily performed.

With such a multistage compression type rotary compressor, when therefrigerant introduction pipe relative to the second rotary compressionelement is opened to the space under the electric element, the distancebetween the first rotary compression element and the intermediatedischarge pipe for discharging the refrigerant is short so that oil isnot sufficiently separated from the refrigerant, and hence excessive oilis sucked in the second rotary compression element. In such a case,since the amount of oil which is discharged from the second rotarycompression element into an external refrigeration circuit through therefrigerant discharge pipe becomes large, the lubricating and sealingperformance in the hermetic shell case of the rotary compressor isdeteriorated, causing a problem of an adverse affect in therefrigeration circuit by the oil.

If the refrigerant introduction pipe relative to the second rotarycompression element is opened to the space over the electric element tosolve the foregoing problem, there arises another problem that a heightdimension of the compressor is enlarged as a whole. Further, therearises still another problem that the oil discharged from the upper endof the rotary shaft is prone to flow into the refrigerant introductionpipe, to induce inconvenience like the foregoing problems.

SUMMARY OF THE INVENTION

The invention has been developed to solve the conventional technicalproblems and it is a first object of the invention to provide aninternal intermediate pressure multistage compression type rotarycompressor capable of reducing a height dimension while reducing theamount of oil to be discharged outside, and of effectively avoiding suchan inconvenience that an excessive oil is sucked in the second rotarycompression element and discharged outside.

Although the hermetic shell case, the electric element, the rotarycompression mechanism or the like constituting the rotary compressor aremanufactured by cutting materials of components, welding and the like,there was a case where a foreign matter such as dust, a cut waste or thelike remains in the hermetic shell case. Further, if the rotarycompressor is connected to an external refrigerant pipe, there is alikelihood that a similar foreign matter in the refrigeration circuit issucked in the refrigerant pipe.

With such a multistage compression type rotary compressor, since theintermediate pressure refrigerant which is discharged into the hermeticshell case from the first stage (first rotary compression element) isintroduced into the second stage (second rotary compression element)through the refrigerant introduction pipe which is directly connected tothe hermetic shell case, if a foreign matter such as dust, a cut wasteor the like is present in the hermetic shell case, the foreign matter issucked in the second stage together with the refrigerant through therefrigerant introduction pipe, involving in the risk of the abrasion inthe second rotary compression element and the locking in the secondrotary compression element in the worst case.

The invention has been developed to solve such conventional technicalproblems, and it is a second object of the invention to provide amultistage compression type rotary compressor to solve the problems ofthe occurrence of abrasion and locking in the second rotary compressionelement by eliminating the foreign matter in the rotary compressor.

With such a multistage compression type rotary compressor, although therefrigerant which is compressed by the second rotary compression elementis discharged outside as it is, the oil supplied to the sliding portionsof the second rotary compression element is mixed in the refrigerant, sothat the oil is discharged together with the refrigerant. Accordingly,there arises a problem that a large amount of oil flows into therefrigeration circuit in the refrigerating cycle, thereby deterioratingthe performance of refrigerating cycle.

Further, with such an internal intermediate pressure multistagecompression type rotary compressor, since a pressure (high pressure)inside the cylinder of the second rotary compression element is higherthan that (intermediate pressure) inside the hermetic shell case havingthe bottom serving as the oil reservoir, it was difficult to supply oilto the second rotary compression element utilizing the difference inpressure.

The invention has been developed to solve such technical problems, andit is a third object of the invention to provide a multistagecompression type rotary compressor capable of reducing the amount of oilwhich is discharged into the outside of the compressor, and of supplyingoil to the second rotary compression element smoothly without fail.

Still further, a vane attached to the multistage compression type rotarycompressor is movably inserted into grooves provided in the radialdirection of the cylinder. Such a vane is pressed by a roller topartition the interior of the cylinder into a low pressure chamber and ahigh pressure chamber, wherein there are provided at the back side ofthe vane a spring and a back pressure chamber for urging the vane to theroller. The back pressure chamber normally communicates with theinterior of the hermetic shell case, and high pressure refrigerant whichis compressed by the second rotary compression element and dischargedinto the hermetic shell case flows into the back pressure chamber so asto urge the vane against the roller together with the spring.

However, if there is proposed an internal high pressure multistagecompression type rotary compressor as set forth above, the pressureinside the hermetic shell case becomes very high so that if the pressure(high pressure) in the hermetic shell case is supplied to the backpressure chamber of the first rotary compression element, the differencebetween the pressure (from the lower pressure to the intermediatepressure) in the cylinder of the first rotary compression element andthat (high pressure) in the back pressure chamber becomes too large, sothat the pressure for pressing the vane against the roller becomes highrequired more than necessary. As a result, a contact pressure is heavilyapplied to the sliding portions of the tip end of the vane and the outerperipheral surface of the roller so that abrasion in the vane and rollerproceeds and there is a likelihood that the vane and roller are damaged.

Since the difference in pressure between the pressure inside thecylinder of the first rotary compression element and that of the backpressure chamber becomes large (high pressure ranging from the lowpressure to the intermediate pressure), the high pressure refrigerant inthe hermetic shell case flows into the cylinder through a clearance ofthe vane of the first rotary compression element, thereby arising aproblem of the lowering the compression efficiency.

The invention has been developed to solve such a conventional problem,and a fourth object of the invention can provide a multistagecompression type rotary compressor capable of improving durability ofthe vane and the roller of the first rotary compression element, and ofimproving the compression efficiency even if the pressure in theinternal of the hermetic shell case is rendered high.

When such an internal intermediate pressure multistage compression typerotary compressor is used at a district such as a cold district where anambient temperature is low, the discharge pressure of the refrigerantwhich is compressed by the first rotary compression element becomes low,and hence the stage pressure of the second stage (the difference inpressure between the suction pressure of the second rotary compressionelement and the discharge pressure of the second rotary compressionelement) becomes large, arising a problem that the compression load ofthe second rotary compression element is increased while the durabilityand reliability of the compressor is lowered. Accordingly, the stagepressure of the second stage has been conventionally restrained byrendering displacement of the second rotary compression element 234smaller by changing many components such as eccentric portions of theroller and the rotary shaft as shown at a right side in FIG. 5.

However, if the displacement ratio of the first rotary compressionelement relative to that of the second rotary compression element is setat an optimum value by changing many components of the rollers and thelike of the second rotary compression element, there arises a problemthat the cost (including the cost involved in the change of materialmold, process facility and measuring equipment and the like) increases.

Further, since the balance of the rotary shaft having the eccentricportion is changed by changing each component of the second rotarycompression element, it is necessary to change a balance weight attachedto the electric element of the compressor for adjusting the balance ofthe rotary shaft.

The invention has been developed to solve such a conventional problem,and it is a fifth object of the invention to provide a multistage rotarycompressor capable of easily setting an optimum displacement ratio whilereducing the cost, and also provide a method of setting the displacementratio thereof.

That is, according to the internal intermediate pressure multistagecompression type rotary compressor of the first aspect of the invention,since a refrigerant introduction pipe is provided such that a part of aninlet of the refrigerant introduction pipe is positioned under the upperend of the stator of the electric element, the amount of oil which issucked in the refrigerant introduction pipe and is discharged from thesecond rotary compression element to the outside compared with a casewhere the refrigerant introduction pipe is opened to the space under theelectric element.

According to the second aspect of the invention, since adjusting meansfor adjusting the inner diameter of an oil discharge port of an oil pathis provided in addition to the constituents of the first aspect of theinvention, the amount of oil to be sucked in the second rotarycompression element can be preferably adjusted while reducing the amountof oil discharged outside.

According to the rotary compressor of the third aspect of the invention,since a notch communicating with the interior of the hermetic shell caseis formed on the side surface of the stator of the electric element, andthe inlet of the refrigerant introduction pipe corresponds to the notchof the stator, the amount of oil which is sucked in the refrigerantintroduction pipe and discharged from the second rotary compressionelement to the outside can be more reduced compared with a case wherethe refrigerant introduction pipe is opened to the space under theelectric element.

According to the rotary compressor of the fourth aspect of theinvention, since a notch of the stator is provided in addition to theconstituents of the third aspect of the invention such that the upperend thereof is opened to the interior of the hermetic shell case overthe electric element, and the lower end thereof is closed so that therefrigerant over the electric element can smoothly flow into therefrigerant introduction pipe, thereby solving the problem of thelowering of oil separation performance involved in the provision of thenotch.

According to the rotary compressor of the fifth aspect of the invention,since adjusting means for adjusting the inner diameter of an oildischarge port of the oil path is provided in addition to theconstituents of the third and fourth aspects of the invention, theamount of oil which is sucked in the second rotary compression elementcan be preferably adjusted while reducing the amount of oil dischargedoutside.

According to the rotary compressor of the sixth and seventh aspects ofthe invention, since the refrigerant in the hermetic shell case over theelectric element is introduced into the second rotary compressionelement, and the amount of oil which is discharged through the oildischarge port of the oil path formed in the rotary shaft and ispositioned at the upper end of the rotary shaft is adjusted by adjustingan inner diameter of the oil discharge port, oil in the hermetic shellcase can be smoothly separated from the refrigerant and the amount ofoil to be sucked in the second rotary compression element can bepreferably adjusted.

Still further, according to the multistage compression type rotarycompressor of the eighth aspect of the invention, since the refrigerantintroduction pipe for introducing the refrigerant in the hermetic shellcase into the second rotary compression element through the outside ofthe hermetic shell case and a filtering means provided at the inlet sideof the refrigerant introduction pipe, a foreign matter which is suckedfrom the hermetic shell case in the refrigerant introduction pipe can becaught and removed by the filtering means. Accordingly, it is possibleto provide the rotary compressor having high reliability capable ofavoiding the problem of the occurrence of abrasion or locking which iscaused by the suction of the foreign matter in the second rotarycompression element in advance.

According to the multistage compression type rotary compressor of theninth aspect of the invention, since the refrigerant introduction pipefor introducing the refrigerant in the hermetic shell case into thesecond rotary compression element through the outside of the hermeticshell case and a filtering means provided at the outlet side of therefrigerant introduction pipe, a foreign matter which is sucked from thehermetic shell case in the second rotary compression element through therefrigerant introduction pipe can be caught and removed by the filteringmeans. Accordingly, it is possible to provide the rotary compressorhaving high reliability capable of avoiding the problem of theoccurrence of abrasion or locking which is caused by the suction of theforeign matter in the second rotary compression element in advance.

According to the multistage compression type rotary compressor of thetenth aspect of the invention, since the refrigerant introduction pipefor introducing the refrigerant in the hermetic shell case into thesecond rotary compression element through the outside of the hermeticshell case and a filtering means provided at the interior of therefrigerant introduction pipe, a foreign matter which is sucked from thehermetic shell case in the refrigerant introduction pipe can be caughtand removed by the filtering means. Accordingly, it is possible toprovide the rotary compressor having high reliability capable ofavoiding the problem of the occurrence of abrasion or locking which iscaused by the suction of the foreign matter in the second rotarycompression element in advance.

According to the multistage compression type rotary compressor of theeleventh aspect of the invention, since the refrigerant compressed bythe second rotary compression element having a pressure which becomeshigher than the pressure of the first rotary compression element isdischarged into the hermetic shell case and the high pressurerefrigerant in the hermetic shell case is discharged outside, oilcontained in the refrigerant discharged from the second rotarycompression element can be separated from the refrigerant in thehermetic shell case. Accordingly, the oil separation performance isimproved and the amount of oil which flows outside from the compressoris reduced, thereby restraining adverse affect exerted upon an externalrefrigerating cycle.

According to the multistage compression type rotary compressor of thetwelfth aspect of the invention, since the refrigerant compressed by thesecond rotary compression element having a temperature which becomeshigher than the temperature of the first rotary compression element isdischarged into the hermetic shell case and the high pressurerefrigerant in the hermetic shell case is discharged outside, oilcontained in the refrigerant discharged from the second rotarycompression element can be separated from the refrigerant in thehermetic shell case. Accordingly, the oil separation performance isimproved and the amount of oil which flows outside from the compressoris reduced, thereby restraining adverse affect exerted upon an externalrefrigerating cycle.

Particularly, since a cylinder constituting the first rotary compressionelement, a back pressure chamber for applying a back pressure to a vanewhich is brought into contact with a roller eccentrically rotated in thecylinder and partitions the interior of the cylinder into a highpressure chamber and low pressure chamber, and a discharge side of thefirst rotary compression element communicate with one another, theintermediate pressure refrigerant which is compressed by the firstrotary compression element is supplied to the back pressure chamber ofthe vane of the first rotary compression element so that the vane isurged toward the roller.

According to the rotary compressor of the thirteenth aspect of theinvention, since a refrigerant introduction pipe for introducing therefrigerant which is discharged from the first rotary compressionelement into the second rotary compression element through the outsideof the hermetic shell case, the temperature of the refrigerant which issucked in the second rotary compression element can be lowered.

According to the rotary compressor of the fourteenth aspect of theinvention, since the first and second rotary compression elements aredisposed under the electric element, and the first rotary compressionelement is disposed under the second rotary compression element, and therefrigerant in the hermetic shell case is discharged outside from thespace over the electric element, in addition to the constituents of theforegoing aspects of the invention, oil separation performance forseparating oil from the high pressure refrigerant in the hermetic shellcase can be further enhanced.

According to the rotary compressor of the fifteenth aspect of theinvention, carbon dioxide having a large difference in pressure betweenhigh and low pressures is used as the refrigerant.

According to the multistage compression type rotary compressor of thesixteenth aspect of the invention, since an upper cylinder constitutingthe second rotary compression element is expanded outward from a suctionport to an extent of a predetermined angle in a direction of rotation ofan upper roller, the start of compression of the refrigerant in thecylinder of the second rotary compression element is delayed.

According to a method of the seventeenth aspect of the invention, sincea ratio of the displacement of the first rotary compression elementrelative to that of the second rotary compression element is set byexpanding the upper cylinder of the second rotary compression elementoutward from a suction port to an extent of a predetermined angle in adirection of rotation of an upper roller to adjust an angle throughwhich the compression by the second rotary compression element starts,the start of compression of the refrigerant in the cylinder of thesecond rotary compression element is delayed, thereby reducing thedisplacement of the second rotary compression element.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional side view of an internal intermediatepressure multistage compression type rotary compressor according to afirst embodiment of the invention;

FIG. 2 is a plan view of a cylinder of a first rotary compressionelement of the rotary compressor in FIGS. 1, 6, 12 and 14;

FIG. 3 is a longitudinal sectional side view of the upper portion of arotary shaft of the rotary compressor in FIGS. 1, 6 and 12;

FIG. 4 is a plan view of a rotary shaft of the rotary compressor in FIG.1;

FIG. 5 are schematic longitudinal sectional views of the rotarycompressors showing the comparison between a height of the rotarycompressor in FIG. 1 and a height of the conventional rotary compressorprovided with an inlet of a refrigerant introduction pipe under theelectric element;

FIG. 6 is a longitudinal sectional side view of an internal intermediatepressure multistage compression type rotary compressor according to asecond embodiment of the invention;

FIG. 7 is a sectional plan view of the rotary compressor in FIG. 6;

FIG. 8 is an enlarged sectional view showing a notch of a stator of therotary compressor in FIG. 6;

FIG. 9 is a longitudinal sectional plane view of an internalintermediate pressure multistage compression type rotary compressoraccording to a modified embodiment of the invention;

FIG. 10 is an enlarged sectional view showing a plane portion of astator of the rotary compressor in FIG. 9;

FIG. 11 are schematic longitudinal sectional views showing thecomparison between a height of a rotary compressor in the case where arefrigerant introduction pipe is opened to the upper end of a stator ofan electric element of a rotary compressor and a height of the rotarycompressor of the modified embodiment of the invention;

FIG. 12 is a longitudinal sectional side view of an internalintermediate pressure multistage compression type rotary compressoraccording to another modified embodiment of the invention;

FIG. 13 is a longitudinal sectional side view of the internalintermediate pressure multistage compression type rotary compressorhaving a refrigerant introduction pipe connected to an electric elementwhich is a contrast example used for explaining the invention of FIG.12;

FIG. 14 is a longitudinal sectional side view of an internalintermediate pressure multistage compression type rotary compressoraccording to a third embodiment of the invention;

FIG. 15 is a longitudinal sectional side view of an internalintermediate pressure multistage compression type rotary compressoraccording to a still modified example of the invention;

FIG. 16 is a longitudinal sectional side view of an internalintermediate pressure multistage compression type rotary compressoraccording to a fourth embodiment of the invention;

FIG. 17 is a longitudinal sectional side view of an internalintermediate pressure multistage compression type rotary compressoraccording to a fifth embodiment of the invention;

FIG. 18 is a longitudinal sectional side view of an internalintermediate pressure multistage compression type rotary compressoraccording to a sixth embodiment of the invention;

FIG. 19 is a longitudinal sectional side view showing a refrigeratingcycle of an oil supply unit of the rotary compressor in FIG. 18;

FIGS. 20 is a longitudinal sectional view showing cylinders of first andsecond rotary compression elements of the rotary compressor in FIG. 18to be used at a normal temperature;

FIG. 21 is longitudinal sectional view of showing cylinders of first andsecond rotary compression elements of the rotary compressor in FIG. 18to be used in a cold district; and

FIG. 22 is a longitudinal sectional view showing a cylinder of a secondrotary compression element of a conventional rotary compressor to beused at normal temperature and in a cold district.

PREFERRED EMBODIMENT OF THE INVENTION

An internal intermediate pressure multistage compression type rotarycompressor, a method of manufacturing thereof and a method of settingdisplacement ratio thereof are described more in detail with referenceto the attached drawings. FIG. 1 is a longitudinal sectional viewshowing the structure of an internal intermediate pressure typemultistage rotary compressor 10 according to a first embodiment of theinvention, and FIG. 2 is a plan view of a cylinder 40 of a first rotarycompression element 32.

In these figures, the rotary compressor 10 is a vertical internalintermediate pressure multistage compression type rotary compressorusing, e.g., carbon dioxide (CO₂) as refrigerant, and the rotarycompressor 10 comprises a cylindrical hermetic shell case 12 made of asteel plate, an electric element 14 which is disposed and accommodatedin the hermetic shell case 12 under the internal space thereof, and arotary compression mechanism 18 comprising a first rotary compressionelement 32 (first stage) and a second rotary compression element 34(second stage) which are disposed under the electric element 14 anddriven by a rotary shaft 16 of the electric element 14.

The hermetic shell case 12 has a bottom serving as an oil reservoir 58and comprises a shell case body 12A for accommodating the electricelement 14 and the rotary compression mechanism 18 therein, and asubstantially bowl-shaped end cap (cover body) 12B for closing the upperopening of the shell case body 12A, wherein a circular attachment hole12D is formed on the upper surface of the end cap 12B at the centerthereof, and a terminal 20 (wiring thereof is omitted) for supplying apower to the electric element 14 is attached to the attachment hole 12D.

The electric element 14 comprises a stator 22 which is annularlyattached to the hermetic shell case 12 along the inner peripheralsurface of the upper space of the hermetic shell case 12, and a rotor 24which is inserted into and installed in the stator 22 with a slightclearance. The rotor 24 is fixed to the rotary shaft 16 which piercesthe center of the rotor 24 and extends vertically.

The stator 22 comprises a laminated body 26 formed by laminatingdoughnut-shaped electromagnetic steel plates and a stator coil 28 whichis wound around the teeth of the laminated body 26 by a direct winding(concentrating winding) system. The rotor 24 is also formed by alaminated body 30 made of electromagnetic steel plates like the stator22 and a permanent magnet MG is embedded in the laminated body 30.

An intermediate partition plate 36 is sandwiched between the firstrotary compression element 32 and the second rotary compression element34. That is, both the first rotary compression element 32 and the secondrotary compression element 34 of the rotary compression mechanism 18comprise the intermediate partition plate 36, upper and lower cylinders38, 40 which are disposed over and under the intermediate partitionplate 36, upper and lower rollers 46, 48 which are engaged in upper andlower eccentric portions 42, 44 provided on the rotary shaft 16 with a180° phase difference therebetween and eccentrically rotated in theupper and lower cylinders 38, 40, upper and lower vanes 52 (a vane atthe cylinder 38 side is not shown but operates in the same manner) whichare urged by a coil spring 77 (a coil spring at the cylinder 38 side isnot shown but operates in the same manner) and a back pressure to bebrought into contact with the upper and lower rollers 46, 48 at each tipend thereof so as to partition the interior of the upper and lowercylinders 38, 40 into a lower pressure chamber LR and a high pressurechamber HR respectively, and an upper support member 54 and a lowersupport member 56 as supporting members also serving as bearings of therotary shaft 16 by closing an upper opening face of the upper cylinder38 and a lower opening face of the lower cylinder 40.

Meanwhile, both the upper support member 54 and the lower support member56 have a suction path 60 (suction path at the upper support member 54side is not shown) communicating with the interior of the upper andlower cylinders 38, 40 by a suction port 55 (upper support member 54 isnot shown in FIG. 2), and noise eliminating chambers 62, 64 formed byrecessing a part of the upper and lower support members, 54, 56 andclosing the recessed portions by an upper cover 66 and a lower cover 68.

The noise eliminating chamber 64 and the interior of the hermetic shellcase 12 communicate with each other through a communication port, notshown, which pierces the upper and lower cylinders 38, 40, theintermediate partition plate 36 and the upper and lower support members54, 56, and an intermediate discharge pipe 121 communicating with thecommunication path is provided upright on the upper support member 54which becomes an upper end of the communication path. The intermediatepressure refrigerant (oil is dissolved therein) which is compressed bythe first rotary compression element 32 is once discharged into thehermetic shell case 12 under the electric element 14 through theintermediate discharge pipe 121 (black arrows in FIG. 1).

At this time, although oil which lubricates and seals the interior ofthe first rotary compression element 32 is dissolved in the refrigerantwhich is discharged into the hermetic shell case 12 under intermediatepressure, this oil is separated from the refrigerant and stuck to theinner surface of the hermetic shell case 12, then transmitted along theinner surface of the hermetic shell case 12 through a space between aplain portion 22C of the stator 22, described later, and the hermeticshell case 12, and it is returned to the oil reservoir 58 at the bottomof the hermetic shell case 12.

Fixed onto the side surface of the shell case body 12A of the hermeticshell case 12 through welding are the suction paths 60 (upper path isnot shown) of the upper support member 54 and the lower support member56, sleeves 141, 143 at the position corresponding to the noiseeliminating chamber 62 and the upper support member 54, a sleeve 142 atthe position corresponding to the lower support member 56, and a sleeve144 at the position corresponding to a notch 22A, described later,formed on the upper end portion (upper end portion of the shell casebody 12A positioned under of the end cap 12B) of the stator 22 of theelectric element 14 and the stator 22.

One end of a refrigerant introduction pipe 92 for introducing therefrigerant in the upper cylinder 38 is inserted into and connected tothe sleeve 141, and it communicates with a suction path, not shown, ofthe upper cylinder 38. In this case, the refrigerant introduction pipe92 is provided in the manner that an inlet 92A (the other end) thereofis positioned in the vicinity of the upper portion of the stator 22 ofthe electric element 14. The refrigerant introduction pipe 92 which isfixed to the sleeve 141 through welding extends to the outside of thehermetic shell case 12 and reaches the sleeve 144, and the other endthereof is inserted into and connected to the interior of the sleeve144, while the inlet 92A is positioned at the interior of the sleeve 144and communicates with and is opened to a space in the hermetic shellcase 12 over the electric element 14 at the portion immediately abovethe upper portion of the stator 22 of the electric element 14.Consequently, the intermediate pressure refrigerant discharged into thehermetic shell case 12 flows from the space over the electric element 14into the refrigerant introduction pipe 92, and passes through theoutside of the hermetic shell case 12 and it is sucked into the uppercylinder 38. In this case, the sleeve 144 is fixed to the shell casebody 12A of the hermetic shell case 12 through welding in the mannerthat a part of the lower side of the inlet 92A of the refrigerantintroduction pipe 92 (about one third of the lower side of the inlet 92Ain the first embodiment) is positioned under the upper end of the stator22 of the electric element 14, while most part of the upper side of theinlet 92A (about two thirds) is positioned over the upper end of thestator 22.

In order to attach the sleeve 144 to the shell case body 12A such thatthe entire of the inlet 92A of the refrigerant introduction pipe 92 isopened to the upper space of the hermetic shell case 12 over the stator22, the dimensions of the shell case body 12A which positioned over thestator 22 needs be relatively higher. However, since the refrigerantintroduction pipe 92 is provided such that a part of the inlet 92A ofthe refrigerant introduction pipe 92 is positioned under the upper endof the stator 22 of the electric element 14, the position of the sleeve144 (the position of the inlet 92A of the refrigerant introduction pipe92) is lowered. As a result, a height dimension of the entire rotarycompressor 10 is reduced.

The inlet 92A of the refrigerant introduction pipe 92 which is fixed tothe sleeve 144 through welding communicates with and is opened to thespace in the hermetic shell case 12 positioned over the electric element14, and the refrigerant introduction pipe 92 per se extends to theoutside of the hermetic shell case 12, and it is inserted into andconnected to the interior of the sleeve 141. As a result, theintermediate pressure refrigerant discharged into the hermetic shellcase 12 flows into the refrigerant introduction pipe 92 from the spaceover the electric element 14, and passes through the outside of thehermetic shell case 12 (it is cooled under intermediate pressure duringthis period), then it is sucked into the upper cylinder 38.

The sleeve 142 is fixed to the hermetic shell case 12 through welding atthe side surface of the lower cylinder 40 corresponding to the firstrotary compression element 32. An end of a refrigerant introduction pipe94 through which the refrigerant is introduced into the lower cylinder40 is inserted into and connected to the sleeve 142, and it communicateswith the suction path 60 of the lower cylinder 40. The other end of therefrigerant introduction pipe 94 is connected to an accumulator, notshown. A refrigerant discharge pipe 96 is inserted into and connected tothe sleeve 143, and one end of the refrigerant discharge pipe 96communicates with the noise eliminating chambers 62.

The operation of the first rotary compression element 32 is nowdescribed with reference to FIG. 2. A discharge port 70 whichcommunicates with the noise eliminating chamber 64 via a dischargevalve, not shown, and the suction port 55 are formed in the lowercylinder 40, wherein guide grooves 71 which extend in the radialdirection are formed in the lower cylinder 40 between the discharge port70 and the suction port 55. The vane 52 is slidably accommodated in theguide grooves 71. The vane 52 partitions the interior of the lowercylinder 40 into a lower pressure chamber LR and a high pressure chamberHR by allowing the tip end thereof to be brought into contact with thelower roller 48, as set forth above. The suction port 55 is opened tothe lower pressure chamber LR while the discharge port 70 is opened tothe high pressure chamber HR.

An accommodation portion 78 which communicates with the guide grooves 71is positioned outside the guide groove 71 (hermetic shell case 12 side)and formed in the Lower cylinder 40. The coil spring 77 is accommodatedin the accommodation portion 78, and a come off prevention member 80 isinserted into and fixed to the accommodation portion 78. The tip end ofthe vane 52 is always urged against the lower roller 48 by the urgingforce of the coil spring 77. Although the structure of the second rotarycompression element 34 is basically the same as the foregoing firstrotary compression element 32, it is needless to say that the dimensionsof the each component are differentiated.

Meanwhile, an oil path 82 is provided in the rotary shaft 16 and extendsvertically while piercing the center of the rotary shaft 16, and thelower end of the oil path 82 communicates with an oil pump (not shown)for pumping up the oil from the oil reservoir 58 provided at the bottomof the hermetic shell case 12, and the upper end of the oil path 82 isopened to the upper sapce in the hermetic shell case 12 over the stator22 at an oil discharge port 82A. The oil path 82 also communicates withsliding portions of both the first and second rotary compressionelements 32, 34.

On the other hand, an auxiliary discharge member 84 (corresponding toadjusting means of the invention) is provided in the oil discharge port82A at the upper end of the oil path 82 (FIG. 3, FIG. 4). The auxiliarydischarge member 84 is opened to the upper space and cylindrical and hasa bottom and it is fixed to the oil discharge port 82A of the oil path82 by pressing.

The auxiliary discharge member 84 has an oil discharge port 84A having apredetermined port diameter (inner diameter) at the center of the bottomsurface thereof by one spot. The auxiliary discharge member 84 ispositioned at the upper end of the rotary shaft 16 and closes the oildischarge port 82A of the oil path 82, thereby adjusting the amount ofoil in a direction to narrow the inner diameter of the oil path 82 ofthe rotary shaft 16 by the oil discharge port 84A formed at the closedbottom. The inner diameter of the oil discharge port 84A is set at asize such that the oil can preferably lubricate the cooling and slidingportions of the electric element 14 in the hermetic shell case 12 andthe amount of oil sucked by the second rotary compression element 34 viathe refrigerant introduction pipe 92 becomes an appropriate value. As aresult, the amount of oil sucked by the second rotary compressionelement 34 as it is and discharged outside can be reduced while securingthe circulation and sealing performance in the second rotary compressionelement 34. Meanwhile, the size of the oil discharge port 84A of theauxiliary discharge member 84 is appropriately determined in conformitywith the size of the rotary compressor 10, and the amount of oil to bedischarged can be adjusted by inserting and disposing a plurality ofauxiliary discharge members 84 into the rotary shaft 16 in the mannerthat the oil discharge ports 84A do not overlap with one another whilethe oil discharge ports 84A are displaced from the central position. Theoperation of the auxiliary discharge member 84 is described later.

FIG. 6 is a longitudinal sectional view showing the structure ofinternal intermediate pressure multistage compression type rotarycompressor 10 provided with first and second rotary compression elements32, 34 according to a second embodiment of the invention. Theconstituents or components in FIG. 6 which are the same as those in FIG.1 are depicted by the same reference numerals. The components in otherembodiments except FIG. 6 which are the same as those in FIG. 1 are alsodepicted by the same reference numerals. An inlet 92A (other end) of arefrigerant introduction pipe 92 in FIG. 6 is inserted into andconnected to the interior of a sleeve 144 and is opened thereto, and thesleeve 144 communicates with an interior of a notch 22A, describedlater, formed in a stator 22 of an electric element 14.

The notch 22A is formed at the upper portion of the side surface of thestator 22 and the upper end thereof communicates with the interior ofthe hermetic shell case 12 over the electric element 14, and the lowerend thereof is closed (FIG. 7, FIG. 8). The periphery of the stator 22has engagement portions 22B which engage in the inner surface of theshell case body 12A of the hermetic shell case 12 at substantially thesame distance, and plane portions 22C formed by notching which do notcontact the inner surface of the shell case body 12A of the hermeticshell case 12 with a predetermined clearance (upper and lower portionthereof are opened to the interior of the hermetic shell case 12)between the shell case body 12A of the hermetic shell case 12 and theplane portions 22C (FIG. 7). These engagement portions 22B and planeportions 22C are alternately formed by twelve spots, and the notch 22Ais formed in such a manner that one of the engagement portions 22B isnotched in a direction from an end cap 12B at the upper portion towardan oil reservoir 58 at the lower portion by a predetermined dimension(reaching slightly lower side from the center of the stator 22 accordingto the second embodiment)

The notch 22A is provided in correspondence with the sleeve 144 and isnotched in width by the shape substantially the same or slightly greaterthan the inlet 92A of the refrigerant introduction pipe 92, and itcommunicates with the interior of the hermetic shell case 12 over theelectric element 14 and also with the inlet 92A of the refrigerantintroduction pipe 92. The notch 22A is provided for sucking therefrigerant which is discharged into the hermetic shell case 12 throughan intermediate discharge pipe 121 and moved upward over the electricelement 14.

A clearance between the plane portions 22C and inner surface of thehermetic shell case 12 communicates with the interior of hermetic shellcase 12 over and lower the stator 22 for moving the refrigerant which isdischarged under the electric element 14 upward, and flowing oil whichis stuck to the inner surface of the hermetic shell case 12 downwardtoward the oil reservoir 58 at the bottom of the hermetic shell case 12.An oil escape path through which oil is escaped toward the other planeportions 22C or under the electric element 14 may be provided at theposition which is located under the inlet 92A of the notch 22A. Withsuch a structure, the problem of introduction of oil, which flowsdownward toward the interior of the notch 22A and flows into therefrigerant introduction pipe 92 is solved. The operation thereof isdescribed later.

FIG. 14 is a longitudinal sectional view showing the structure ofinternal intermediate pressure multistage compression type rotarycompressor 10 provided with first and second rotary compression elements32, 34 according to a third embodiment of the invention. A filter 130(filtering means of the invention) is provided in an inlet 92A of arefrigerant introduction pipe 92. The filter 130 catches and filters aforeign matter such as dust and a cut waste mixed in refrigerant whichis circulated in a refrigeration circuit including a hermetic shell case12, and it has an opening portion 130A formed at one end and a tip endportion 130B which is tapered from the opening portion 130A toward theother end thereof, representing substantially conical shape. The filter130 partitions the interior of the inlet 92A of the refrigerantintroduction pipe 92 into an inner side of the hermetic shell case 12(upstream side) and an inner side of the refrigerant introduction pipe92 (downstream side) so that it is mounted in the inlet 92A such thatthe opening portion 130A is brought into intimate contact with the innersurface of the refrigerant introduction pipe 92 so that all the foreignmatters entering from the hermetic shell case 12 into the refrigerantintroduction pipe 92 can be filtered. As a result, the foreign mattersuch as a dust and cut waste remaining in the hermetic shell case 12 canbe filtered by the filter 130. Although the filter 130 is attached tothe interior of the inlet 92A of the refrigerant introduction pipe 92according to the third embodiment shown in FIG. 14, it may be attachedto an interior of a sleeve 144 at the front portion of the refrigerantintroduction pipe 92 (inner side of the hermetic shell case 12), and thelike.

When the filter 130 catches the foreign matter, the opening portion 130Ais disposed in a direction of the upstream side of the refrigerantintroduction pipe 92 while the tip end portion 130B is disposed in adirection of the downstream side of the refrigerant introduction pipe 92so that the path in the refrigerant introduction pipe 92 is not blockedoff by the foreign matter. That is, the filter 130 is mounted in therefrigerant introduction pipe 92 in the manner that the opening portion130A is positioned at the inlet 92A of the refrigerant introduction pipe92 (upstream side of the refrigerant) and the tip end portion 130B ispositioned at the downstream side of the refrigerant gas. Further, thefilter 130 is formed of a wire mesh, a synthetic resin mesh, or asynthetic resin which can filter the foreign matter such as a dust and acut waste remaining in the hermetic shell case 12, and is not easilydeteriorated by refrigerant which is sealed in the hermetic shell case12 or an oil which is dissolved into the refrigerant gas, and is noteasily broken when filtering the foreign matter such as a dust and a cutwaste.

There is a possibility that the foreign matter such as a dust, weldingwaste and the like which are produced by cutting and welding a materialof components such as the hermetic shell case 12, the electric element14 or the rotary compression mechanism 18 and the like remains in thehermetic shell case 12 constituting the rotary compressor 10. In such acase, although the foreign matter such as a dust, or a cut wasteproduced by cutting or welding the material of the components whenmanufacturing the rotary compressor 10 is removed by cleaning, there isa possibility that such a foreign matter is not cleaned but remains inthe hermetic shell case 12 and also the foreign matter can be suckedfrom an external refrigeration circuit, and hence the filter 130 of theinvention is provided for filtering such the foreign matter.

FIG. 17 is a longitudinal sectional view showing the structure of aninternal intermediate pressure multistage compression type rotarycompressor 10 provided with first and second rotary compression elements32, 34 according to a fourth embodiment of the invention. The rotarycompressor 10 of the invention is an internal high pressure typemultistage rotary compressor, described later.

In FIG. 17, the multistage compression type rotary compressor 10comprises a cylindrical hermetic shell case 12 comprised of acylindrical shell case body 12A made of a steel plate and asubstantially bowl-shaped end cap (cover body) 12B for closing the upperopening of the shell case body 12A, an electric element 14 which isdisposed and accommodated in the hermetic shell case 12 at the upperside of the internal space thereof, and a rotary compression mechanism18 comprising first rotary compression element 32 and a second rotarycompression element 34 which are disposed under the electric element 14and driven by a rotary shaft 16 of the electric element 14.

The hermetic shell case 12 has a bottom serving as an oil reservoir 58.A circular attachment hole 12D is formed on the upper surface of the endcap 12B at the center thereof, and a terminal 20 (wiring thereof isomitted) for supplying a power to the electric element 14 is attached tothe attachment hole 12D. Since the interior of the hermetic shell case12 is rendered high pressure, it assumes that the terminal 20 becomesinternal high pressure matching type, and it is not welded at thecentral pipe.

The electric element 14 comprises a stator 22 which is annularlyattached to the hermetic shell case 12 along the inner surface of theshell case body 12A in the upper space of the hermetic shell case 12,and a rotor 24 which is inserted into and installed in the stator 22with a slight clearance between the rotor 24 and the inner side of thestator 22. The rotor 24 is fixed to the rotary shaft 16 which extendsvertically.

The stator 22 comprises a laminated body 26 formed by laminatingdoughnut-shaped electromagnetic steel plates and a stator coil 28 whichis wound around the teeth of the laminated body 26 by a direct winding(concentrating winding) system. The rotor 24 is also formed by alaminated body 30 made of electromagnetic steel plates like the stator22 and a permanent magnet MG is embedded in the laminated body 30. Afterthe permanent magnet MG is inserted into the laminated body 30, upperand lower end faces of the laminated body 30 are covered withnon-magnetic end face members, and a balance weight 101 (a balanceweight at the lower side of the laminated body 30 is not shown) isattached to the face of the end face member which does not-contact thelaminated body 30, and further an oil separation plate 102 is attachedto the upper side of the balance weight 101, positioned over thelaminated body 30 while overlapping therewith. These rotor 24, thebalance weight 101, the oil separation plate 103 are pierced by a rivet104 and they are integrated with one another.

An oil separation plate 103 is attached to the end portion (upper endportion) of the electric element 14 side of the rotary shaft 16 andpositioned over the rotor 24. Meanwhile, an oil pump 102 serving as anoil supply means is formed at the end portion (lower end portion) of thefirst rotary compression element 32 side of the rotary shaft 16. The oilpump 102 is provided for pumping up oil for lubrication from the oilreservoir provided on the bottom of the hermetic shell case 12 andsupplying the oil to sliding portions of the rotary compressionmechanism 18 and the like, and preventing abrasion and effectingsealing, a lower end 103 of the oil pump 102 is positioned in the oilreservoir.

A fifth embodiment of the invention is now described in detail. Anintermediate partition plate 36 is sandwiched between a first rotarycompression element 32 and a second rotary compression element 34 inFIG. 17, and the first rotary compression element 32 is positioned underthe intermediate partition plate 36 while the second rotary compressionelement 34 is positioned over the intermediate partition plate 36 (i.e.over the first rotary compression element 32). That is, both the firstand second rotary compression elements 32, 34 comprise the intermediatepartition plate 36, upper and lower cylinders 38, 40 disposed over andunder the intermediate partition plate 36, upper and lower rollers 46,48 which are engaged in upper and lower eccentric portions 42, 44provided on the rotary shaft 16 with a 180° phase differencetherebetween and eccentrically rotated in the upper and lower cylinders38, 40, vanes not shown, which is brought into contact with the upperand lower rollers 46, 48 so as to partition the interior of the upperand lower cylinders 38, 40 into a lower pressure chamber and a highpressure chamber respectively, and an upper support member 54 and alower support member 56 as supporting members also serving as bearingsof the rotary shaft 16 by closing an upper opening face of the uppercylinder 38 and the lower opening face of the lower cylinder 40.

Guide grooves 72 for accommodating the vane 52 are formed in the lowercylinder 40 constituting the first rotary compression element 32 and anaccommodation portion 72A for accommodating a spring 76 serving as aspring member is formed at the outside of the guide grooves 72, namely,at the back side of the vane 52. The spring 76 contacts the end portionof the back surface end of the vane 52 to always urge the vane 52against the lower roller 48. The accommodation portion 72A is opened tothe guide grooves 72 and the hermetic shell case 12 (shell case body12A), and a metallic plug 138 is provided at the hermetic shell case 12side of the spring 76 which is accommodated in the accommodation portion72A to prevent the spring 76 from coming off. Further, an O-ring, notshown, for sealing between the metallic plug 138 and the inner surfaceof the accommodation portion 72A is attached to the peripheral surfaceof the metallic plug 138.

Further, a back pressure chamber 52A for applying a refrigerantdischarge pressure of the first rotary compression element 32 to thevane 52 is provided between the guide grooves 72 and the accommodationportion 72A for always urging the spring 76 and the vane 52 toward thelower roller 48. The lower surface of the back pressure chamber 52Acommunicates with a communication path 100, described later. Both theback pressure chamber 52A and the interior of the hermetic shell case 12are separated from each other by the metallic plug 138.

There are provided, in the upper support member 54 and the lower supportmember 56, suction paths 59, 60 which communicate with interiors of theupper and lower cylinders 38, 40 through a suction port 161 (a suctionport of the first rotary compression element 32 is not shown), and noiseeliminating chambers 62, 64 which are formed by closing recessedportions of the upper and lower support members 54, 56 by covers servingas a wall. That is, the noise eliminating chamber 62 is closed by anupper cover 66 as a wall for forming the noise eliminating chamber 62and the noise eliminating chamber 64 is closed by a lower cover 68.

The communication path 100 is formed in the lower support member 56. Thecommunication path 100 is a path for allowing the noise eliminatingchamber 64 which communicates with a discharge port, not shown, of thelower cylinder 40 of the first rotary compression element 32 tocommunicate with the back pressure chamber 52A. The communication path100 communicates with the back pressure chamber 52A at the upper sidewhile communicating with the noise eliminating chamber 64 at the lowerside. Then, the vane 52 of the first rotary compression element 32 isurged against the lower roller 48 by an intermediate pressure ofrefrigerant which is compressed by the first rotary compression element32, and discharged into the noise eliminating chamber 64 through adischarge port, not shown, then passes through the communication path100 and flows into the back pressure chamber 52A.

As a result, the difference in pressure between the interior of thelower cylinder 40 of the first rotary compression element 32 and theback pressure chamber 52A can be reduced compared with the case where apressure inside the hermetic shell case 12 which becomes high pressureis supplied to the vane 52 of the first rotary compression element 32 asa back pressure, and hence the load applied to the tip end of the vane52 can be reduced while preventing a so-called jumping of a vane.Accordingly, the improvement of reliability of the rotary compressor 10can be enhanced.

Further, since the amount of refrigerant which leaks from the guidegrooves 72 of the vane 52 of the first rotary compression element 32 tothe interior of the lower cylinder 40 can be reduced, the improvement ofcompression efficiency can be enhanced.

The lower cover 68 is formed of a doughnut-shaped circular steel plate,and it is fixed to the lower support member 56 by main bolts 129, atfour spots of the periphery thereof from the lower side thereof. Eachtip end of the main bolts 129, is screwed with the upper support member54.

The noise eliminating chamber 64 of the first rotary compression element32 and the suction path 59 of the second rotary compression element 34communicate with each other by the refrigerant introduction pipe 92. Therefrigerant introduction pipe 92 is positioned outside the hermeticshell case 12, and the refrigerant discharged into the noise eliminatingchamber 64 passes the outside of the hermetic shell case 12 through therefrigerant introduction pipe 92, and is introduced into the secondrotary compression element 34.

Further, at this time, oil which is supplied to the first rotarycompression element 32 is mixed in the refrigerant which is supplied tothe second rotary compression element 34, and the refrigerant includinga large amount of this oil is directly sucked in the second rotarycompression element 34. Accordingly, a sufficient amount of oil issupplied to the second rotary compression element 34 without trouble.

In such a manner, oil rich refrigerant containing therein oil which issupplied to the first rotary compression element 32 can be introducedinto the second rotary compression element 34 as it is by causing therefrigerant which is compressed by the first rotary compression element32 to be sucked in the second rotary compression element 34 via therefrigerant introduction pipe 92 as it is without being discharged intothe hermetic shell case 12.

Accordingly, it is possible to supply oil to the second rotarycompression element 34 without using a special device for supplying oilto the sliding portions of the second rotary compression element 34, andhence it is possible to solve the problem of short of oil to be suppliedto the second rotary compression element 34.

Further, an oil supply mechanism to supply oil to the second rotarycompression element 34 can be simplified, and hence the manufacturingcost of the oil supply mechanism can be reduced.

Still further, since the refrigerant which is compressed by the firstrotary compression element 32 is introduced into the second rotarycompression element 34 via the refrigerant introduction pipe 92 which isprovided outside the hermetic shell case 12, the refrigerant which iscompressed by the first rotary compression element 32 can be cooledduring the passage through the outside of the hermetic shell case 12. Asa result, it is possible to lower the temperature of the refrigerantwhich is sucked in the second rotary compression element 34, therebyenhancing the improvement of compression efficiency.

The electric element 14 is provided over the upper cover 66 with apredetermined distance between the upper cover 66 and the electricelement 14. The upper cover 66 is fixed to the upper support member 54from the above by four main bolts 78, at the periphery thereof. Each tipend of the main bolts 78, is screwed with the lower support member 56.

The noise eliminating chamber 62 of the second rotary compressionelement 34 and the interior of the hermetic shell case 12 communicatewith each other by a discharge port 120 which pierces the upper cover 66and is opened to the electric element 14 inside the hermetic shell case12, and a high pressure refrigerant which is compressed by the secondrotary compression element 34 is discharged into the hermetic shell case12 through the discharge port 120. At this time, although oil to besupplied to the first and second rotary compression elements 32, 34 ismixed in the refrigerant, this oil is also discharged into the hermeticshell case 12. Then, the oil is separated from the refrigerant duringthe passage through the space inside the hermetic shell case 12, andflows downward into the oil reservoir provided at the bottom of thehermetic shell case 12 and reserved therein.

Carbon dioxide (CO₂) which is natural refrigerant is used as refrigerantin this case considering earth consciousness, inflammability, toxicityor the like, and an existing oil such as mineral oil, alkylbenzene oil,ether oil, ester oil, PAG (polyalkylglycol) or the like is used as theoil of the lubricant.

Sleeves 141, 142, 143 and 144 are respectively fixed to the side surfaceof the shell case body 12A of the hermetic shell case 12 through weldingat the positions corresponding to the suction paths 59, 60 of the uppersupport member 54 and the lower support member 56, the noise eliminatingchamber 64, and the upper portion of the rotor 24 (immediately over theelectric element 14). The sleeves 141 and 142 adjoin vertically eachother and the sleeve 143 is located substantially at a diagonal line ofthe sleeve 142. Further, the sleeve 144 is positioned over the sleeve141. One end of the refrigerant introduction pipe 92 through which therefrigerant is introduced into the upper cylinder 38 is inserted intoand connected to the sleeve 141.

The refrigerant introduction pipe 92 is provided for supplying therefrigerant which is compressed by the first rotary compression element32 to the second rotary compression element 34, as set forth above, andone end of the refrigerant introduction pipe 92 communicates with thesuction path 59 of the upper cylinder 38. The refrigerant introductionpipe 92 extends to the outside of the hermetic shell case 12 and reachesthe sleeve 143 and the other end thereof is inserted into and connectedto the sleevel43 to communicate with the noise eliminating chamber 64 ofthe first rotary compression element 32.

One end of a refrigerant introduction pipe 94 for introducingrefrigerant into the lower cylinder 40 is inserted into and connected tothe sleeve 142, and it communicates with the suction path 60 of thelower cylinder 40. The other end of the refrigerant introduction pipe 94is connected to an accumulator, not shown, constituting therefrigeration circuit.

Further, the refrigerant discharge pipe 96 is inserted into andconnected to the interior of the sleeve 144 and one end of therefrigerant discharge pipe 96 communicates with the interior of thehermetic shell case 12 over the electric element 14. In such a manner,since the refrigerant discharge pipe 96 is provided at the space overthe electric element 14, oil which is discharged into the hermetic shellcase 12 under the electric element 14 together with the refrigerantcompressed by the second rotary compression element 34 passes throughthe electric element 14 and reaches the space over the electric element14 and it is discharged outside through the refrigerant discharge pipe96. In such a manner, since the refrigerant discharged from the secondrotary compression element 34 moves in the space inside the hermeticshell case 12, the oil dissolved in the refrigerant is smoothlyseparated from the refrigerant. Further, since the refrigerant passesthrough an oil separation plate 103 provided over the electric element14 (upper end of the rotary shaft 16), the separation of oil is furtheraccelerated. As a result, the amount of oil discharged outside therotary compressor 10 (in the refrigeration circuit of the refrigeratingcycle) together with the refrigerant can be effectively reduced.

Further, since the oil rich refrigerant is sucked in the second rotarycompression element 34 as set forth above, the increase of thetemperature of the second rotary compression element 34 can berestrained. Accordingly, the increase of temperature of the electricelement 14 is also restrained, resulting in the improvement of theperformance and reliability of the rotary compressor 10.

FIG. 18 is a longitudinal sectional view showing the internalintermediate pressure multistage (two stages) compression type rotarycompressor 10 provided with first and second rotary compression elements32, 34 according to a sixth embodiment of the invention, FIG. 19 is acircuit diagram of a refrigeration circuit in the case where theinvention is applied to a hot water supply unit 153, FIG. 20 issectional views of upper and lower cylinders 38, 40 of the first andsecond rotary compression elements 32, 34 of the rotary compressor 10used at a room temperature, and FIG. 21 is a sectional views of upperand lower cylinders 38, 40 of the first and second rotary compressionelements 32, 34 of the rotary compressor 10 used at a cold district towhich the invention is applied.

In FIG. 18, the stator 22 comprises a laminated body 26 formed bylaminating doughnut-shaped electromagnetic steel plates and a statorcoil 28 which is wound around the teeth of the laminated body 26 by adirect winding (concentrating winding) system. The rotor 24 is alsoformed by a laminated body 30 made of electromagnetic steel plates likethe stator 22 and a permanent magnet MG is inserted into the laminatedbody 30. After the permanent magnet MG is inserted into the laminatedbody 30, upper and lower end faces of the laminated body 30 are coveredwith non-magnetic end face members, not shown, and a balance weight 101(a balance weight under the laminated body 30 is not shown) is attachedto the face which do not contact the laminated body 30 of the end facemember, and further an oil separation plate 102 is attached to the upperside of the balance weight 101 positioned over the laminated body 30while overlapping therewith.

These rotor 24, the balance weight 101, the oil separation plate 102 arepierced by a rivet 104 and they are integrated with one another.

An intermediate partition plate 36 is sandwiched between the firstrotary compression element 32 and the second rotary compression element34. That is, both the first and second rotary compression elements 32,34 comprise the intermediate partition plate 36, upper and lowercylinders 38, 40 disposed over and under the intermediate partitionplate 36, upper and lower rollers 46, 48 which are engaged in upper andlower eccentric portions 42, 44 provided on the rotary shaft 16 with a180° phase difference therebetween and eccentrically rotated in theupper and lower cylinders 38, 40, upper and lower vanes 50, 52 which arebrought into contact with the upper and lower rollers 46, 48 so as topartition the interior of the upper and lower cylinders 38, 40 into alower pressure chamber and a high pressure chamber respectively, and anupper support member 54 and a lower support member 56 as supportingmembers also serving as bearings of the rotary shaft 16 by closing anupper opening face of the upper cylinder 38 and the lower opening faceof the lower cylinder 40.

Although displacement of the second rotary compression element 34 issmaller than that of the first rotary compression element 32, thedisplacement of the second rotary compression element 34 is assumed tobe large, and it is designed to have 65% of the displacement of thefirst rotary compression element 32 in FIG. 20.

There are provided, in the upper and lower support members 54, 56 asuction path 60 (upper suction path is not shown) which communicateswith interiors of the upper and lower cylinders 38, 40 through suctionports 161, 162, and noise eliminating chambers 62, 64 which are formedby closing recessed portions of the upper and lower support members 54,56 by covers serving as a wall. That is, the noise eliminating chamber62 is closed by an upper cover 66 as a wall for forming the noiseeliminating chamber 62 and the noise eliminating chamber 64 is closed bya lower cover 68.

In this case, a bearing 54A is formed upright on the center of the uppersupport member 54. A bearing 56A are formed by piercing the center ofthe lower support member 56, and the rotary shaft 16 is retained by thebearing 54A of the upper support member 54 and the bearing 56A of thelower support member 56.

The lower cover 68 is formed of a doughnut-shaped circular steel plate,and it is fixed to the lower support member 56 by main bolts 129, . . .at four spots of the periphery thereof from the lower side thereof,thereby forming the discharge noise eliminating chamber 64 whichcommunicates with the interior of the lower cylinder 40 of the firstrotary compression element 32 by the discharge port 41. Each tip end ofthe main bolts 129, is screwed with the upper support member 54.

A discharge valve 128 (this is shown in the same plane_in FIGS. 20 and21 as the cylinder for the brevity of explanation) for closably closingthe discharge port 41 is provided on the upper surface of the noiseeliminating chamber 64. The discharge valve 128 is formed of an elasticmember made of a longitudinal substantially rectangular metal plate, andone side of the discharge valve 128 is brought into contact with thedischarge port 41 to seal it while the other side thereof is fixed to anattachment port, not shown, of the lower support member 56 by a caulkingpin with a predetermined interval relative to the discharge port 41.

Further, a bucker valve 128A serving as a discharge valve restrainingplate is disposed under the discharge valve 128, and it is attached tothe lower support member 56 like the discharge valve 128.

The refrigerant which is compressed in the lower cylinder 40 and reachesa predetermined pressure pushes up the discharge valve 128 which closesthe discharge port 41 to open the discharge port 41 so that it isdischarged toward the noise eliminating chamber 64. At this time, sincethe discharge valve 128 is fixed to the lower support member 56 at theother side, one side thereof which is brought into contact with thedischarge port 41 is warped up and is brought into contact with a buckervalve 128A, which restricts the amount of the opening of the dischargevalve 128. When the discharge of the refrigerant approaches an end time,the discharge valve 128 is moved away from the bucker valve 128A toclose the discharge port 41.

The noise eliminating chamber 64 of the first rotary compression element32 and the interior of the hermetic shell case 12 communicate with eachother through a communication port, and the communication is a port, notshown, which pieces the upper cover 66, the upper and lower cylinders38, 40, and the intermediate partition plate 36. In this case, aninter-mediate discharge pipe 121 is provided upright on the upper end ofthe communication path. The intermediate pressure refrigerant isdischarged into the hermetic shell case 12 through the intermediatedischarge pipe 121.

Further, the upper cover 66 forms a discharge noise eliminating chamber62 which communicates with the interior of the upper cylinder 38 of thesecond rotary compression element 34 through the discharge port 39 andthe electric element 14 is provided over the upper cover 66 with apredetermined distance relative to the upper cover 66. The upper cover66 is formed of a doughnut-shaped circular steel plate having a holewhich the bearing 54A of the upper support member 54 pierces, and it isfixed to the upper support member 54 by main bolts 178, at four spots ofthe periphery thereof from the above. Each tip end of the main bolts178, is screwed with the lower support member 56.

A discharge valve 127 (shown in the same plane in FIGS. 20 and 21 as thecylinder for the brevity of explanation) for closably closing thedischarge port 39 is provided on the lower surface of the noiseeliminating chamber 62. The discharge valve 127 is formed of an elasticmember made of a longitudinal substantially rectangular metal plate, andone side of the discharge valve 127 is brought into contact with thedischarge port 39 to seal it while the other side thereof is fixed to anattachment hole, not shown, of the upper support member 54 by a caulkingpin with a predetermined interval relative to the discharge port 39.

Further, a bucker valve 127A serving as a discharge valve restrainingplate is disposed over the discharge valve 127, and it is attached tothe upper support member 54 like the discharge valve 127.

The refrigerant which is compressed in the upper cylinder 38 and reachesa predetermined pressure pushes up the discharge valve 127 (shown in thesame plane in FIGS. 20 and 21 as the cylinder for brevity ofexplanation) which closes the discharge port 39 to open the dischargeport 39 so that it is discharged toward the noise eliminating chamber62. At this time, since the discharge valve 127 is fixed to the uppersupport member 54 at the other side, one side thereof which is broughtinto contact with the discharge port 39 is warped up and is brought intocontact with a bucker valve 127A which restricts the amount of theopening of the discharge valve 127. When the discharge of therefrigerant approaches an end time, the discharge valve 127 is movedaway from the bucker valve 127A to close the discharge port 39.

There are provided in the upper and lower cylinders 38, 40, guidegrooves, not shown, for accommodating the upper and lower vanes 50, 52;and accommodation portions 70, 72 which are positioned outside the guidegrooves and accommodate springs 76, 78 serving as spring members. Theaccommodation portions 70, 72 are opened to the guide grooves and thehermetic shell case 12 (shell case body 12A). The springs 76, 78 arebrought into contact with outer end portions of the upper and lowervanes 50, 52 to always urge the upper and lower vanes 50, 52 against theupper and lower rollers 46, 48. Metal plugs 137, 140 are provided in theaccommodation portions 70, 72 of the springs 76, 78 at the side of thehermetic shell case 12, and serve to prevent the springs 76, 78 fromcoming off.

Sleeves 141, 142, 143 and 144 are respectively fixed to the side surfaceof the shell case body 12A of the hermetic shell case 12 through weldingat the positions corresponding to the suction path 60 (upper side is notshown) of the upper and lower support members 54, 56, the noiseeliminating chamber 62, and the upper portion of the upper cover 66(position substantially corresponding to the lower end of the electricelement 14). The sleeves 141 and 142 adjoin vertically each other andthe sleeve 143 is located substantially at a diagonal line of the sleeve141. Further, the sleeve 144 is positioned while displaced substantially90° relative to the sleeve 141.

One end of a refrigerant introduction pipe 92 for introducing therefrigerant into the upper cylinder 38 is inserted into and connected tothe sleeve 141, and it communicates with a suction path, not shown, ofthe upper cylinder 38. The refrigerant introduction pipe 92, passes overthe hermetic shell case 12 and reaches the sleeve 144, and the other endthereof is inserted into and connected to the sleeve 144 to communicatewith the hermetic shell case 12.

One end of a refrigerant introduction pipe 94 for introducingrefrigerant into the lower cylinder 40 is inserted into and connected tothe sleeve 142, and it communicates with the suction path 60 of thelower cylinder 40. The other end of the refrigerant introduction pipe 94is connected to a lower end of an accumulator, not shown. A refrigerantdischarge pipe 96 is inserted into and connected to the sleeve 143, andone end of the refrigerant discharge pipe 96 communicates with the noiseeliminating chamber 62.

Meanwhile, in the case where multistage compression type rotarycompressor shown in FIG. 20 is used at a district where an ambienttemperature is low such as a cold district or the like, a ratio ofdisplacement ratio of the first rotary compression element 32 relativeto that of the second rotary compression element 34 has to be changed.That is, the displacement ratio has to be changed such that thedisplacement of the second rotary compression element 34 is further madesmall.

In this case, for example, in order to set the displacement of thesecond rotary compression element 34 is set to be 55% of that of thefirst rotary compression element 32, an expansion portion 110 is formedin the upper cylinder 38 as shown in FIG. 21. The expansion portion 110is formed by expanding the upper cylinder 38 outward from a suction port161 to an extent of a predetermined angle in the direction of rotationof an upper roller 46. Owing to the provision of the expansion portion110, it is possible to delay the angle through which compression ofrefrigerant is started by the upper cylinder 38 to the end in thedirection of the rotation of upper roller 46 of the expansion portion110. That is, the start of compression of refrigerant by the uppercylinder 38 can be delayed by the angle within which the expansionportion 110 of the upper cylinder 38 is formed.

Accordingly, the amount of refrigerant compressed in the upper cylinder38 can be reduced, resulting in the reduction of displacement of thesecond rotary compression element 34.

In the seventh embodiment shown in FIG. 21, the angle within which theexpansion portion 110 is formed is adjusted such that the displacementof the second rotary compression element 34 becomes 55% of that of thefirst rotary compression element 32. Accordingly, displacement of thesecond rotary compression element 34 can be reduced without changing thecylinder, the roller, the eccentric portion and the like of the secondrotary compression element 34, and the increase of the pressure in thesecond stage (the difference between the suction pressure of the secondrotary compression element 34 and the discharge pressure of the secondrotary compression element 34) can be prevented.

That is, since the displacement of the second rotary compression element34 can be reduced by merely forming the expansion portion 110 in theupper cylinder 38, it is possible to restrain the increase of costcaused by the change of components.

Furthermore, since the balance weight 101 which is attached to the endsurface of the rotor 24 of the electric element 14 for adjusting thebalance of the rotary shaft 16 is not needed to be changed, the cost canbe further reduced.

The multistage compression type rotary compressor 10 shown in FIG. 19constitutes the refrigeration circuit system of a hot water supply unit153 shown in FIG. 19.

That is, the refrigerant discharge pipe 96 of the multistage compressiontype rotary compressor 10 is connected to a gas cooler 154. The gascooler 154 is provided in a hot water tank, not shown, of the hot watersupply unit 153 in order to heat water to produce hot water. A pipingextended from the gas cooler 154 reaches an inlet of an evaporator 157via an expansion valve 156 serving as a pressure reducing device andconnected to the evaporator 157. The evaporator 157 is connected to therefrigerant introduction pipe 94 via the accumulator, not shown.

Operations in respective embodiments are now described. When the statorcoil 28 of the electric element 14 is energized via the terminal 20 andwiring, not shown, in the multistage compression type rotary compressorin FIG. 1, the electric element 14 is actuated to rotate the rotor 24.When the rotor 24 is rotated, the upper and lower rollers 46, 48 whichare engaged in the upper and lower eccentric portions 42, 44 integrallyprovided with the rotary shaft 16 are eccentrically rotated in the upperand lower cylinders 38, 40.

As a result, low pressure (about 4 MpaG) refrigerant which is sucked inthe low pressure chamber LR of the lower cylinder 40 through the suctionports 55, 162 via the suction path 60 formed in the refrigerantintroduction pipe 94 and the lower support member 56 is subjected tocompression of first stage by the operation of the lower roller 48 andthe lower vane 52 and changed into an intermediate pressure (about 8MpaG). The intermediate pressure refrigerant is discharged into thehermetic shell case 12 under the electric element 14 through theintermediate discharge pipe 121 via the high pressure chamber HR, thenoise eliminating chamber 64 and the communication path. Consequently,the interior of the hermetic shell case 12 becomes intermediatepressure. As a result, the discharge valve 128 provided in the noiseeliminating chamber 64 is opened and the noise eliminating chamber 64and the discharge port 41 communicate with each other, and hence therefrigerant passes from the high pressure chamber HR of the lowercylinder 40 through the interior of the discharge port 41 and isdischarged into the noise eliminating chamber 64 formed in the lowersupport member 56. The refrigerant discharged into the noise eliminatingchamber 64 is discharged into the hermetic shell case 12 through theintermediate discharge pipe 121 via a communication port, not shown.

The intermediate pressure refrigerant discharged into the noiseeliminating chamber 64 flows into the back pressure chamber 52A of thefirst rotary compression element 32 through the communication path 100,thereby urging the vane 52 as well as the spring 76 in a direction ofthe lower roller 48. On the other hand, the other intermediate pressurerefrigerant which is discharged into the noise eliminating chamber 64enters the refrigerant introduction pipe 92 and passes through theoutside of the hermetic shell case 12 and the suction path 59 of thesecond rotary compression element 34, then it is sucked in the lowpressure chamber LR of the upper cylinder 38 through the suction port161. At this time, the refrigerant is cooled when it passes through therefrigerant introduction pipe 92 provided at the outside of the hermeticshell case 12.

The refrigerant discharged through the intermediate discharge pipe 121passes through the electric element 14 and a clearance between theelectric element 14 (depicted by 22C in plan view), and rises upwardover the electric element 14, and passes through the notch 22A, then itis sucked in the refrigerant introduction pipe 92 from the upper portionof two thirds of the inlet 92A of the refrigerant introduction pipe 92.Oil which is dissolved in the refrigerant which is discharged throughthe intermediate discharge pipe 121 is separated from the refrigerantduring the rising of the refrigerant in the hermetic shell case 12, andthe separated oil is stuck to a wall surface of the shell case body 12Aand flows from the plane portions 22C and the like into the oilreservoir 58. Further, the oil discharged through the oil discharge port84A of the auxiliary discharge member 84 provided at the upper end ofthe rotary shaft 16 toward the space over the electric element 14 flowsalong the inner surface of the hermetic shell case 12 as shown by blackarrows and flows into the oil reservoir 58 while lubricating theelectric element 14.

The refrigerant (containing oil, described later) sucked in therefrigerant introduction pipe 92 passes through the interior thereof andalso suction path, not shown, formed in the upper support member 54, andsucked into the low pressure chamber LR of the upper cylinder 38 througha suction port, not shown. What is sucked in the refrigerantintroduction pipe 92 includes a part of oil which is discharged throughthe intermediate discharge pipe 121 and not separated from therefrigerant and also a part of oil discharged through the oil dischargeport 84A of the auxiliary discharge member 84 provided at the upper endof the rotary shaft 16 as well as the refrigerant.

The intermediate pressure refrigerant sucked in the low pressure chamberLR of the upper cylinder 38 is subjected to compressions of second stageby the operation of the upper roller 46 and vane, not shown, and ischanged into high temperature and high pressure refrigerant, which inturn passes from the high pressure chamber HR through the dischargeport, not shown, and also passes through the noise eliminating chamber62 formed in the upper support member 54 and the refrigerant dischargepipe 96, then it is discharged outside, and flows into a gas cooler, notshown.

The refrigerant discharged into the hermetic shell case 12 passesthorough the notch 22A and it is sucked in the second rotary compressionelement 34 through the inlet 92A of the refrigerant introduction pipe92. At this time, although a part of oil which is discharged through theintermediate discharge pipe 121 and not separated from the refrigerantand also a part of oil discharged through the oil discharge port 84A ofthe auxiliary discharge member 84 provided at the upper end of therotary shaft 16 as well as the refrigerant are sucked and flows into thesecond rotary compression element 34 through the inlet 92A of therefrigerant introduction pipe 92, but the oil separation capacity in thehermetic shell case 12 is improved compared with a case where the inlet92A of the refrigerant introduction pipe 92 is opened to the interior ofthe hermetic shell case 12 under the electric element 14, as shown inthe left side in FIG. 5 (respectively rotary compressor 200).

Particularly, since the inner diameter of the oil discharge port 84A isset at the size such that the electric element 14 inside the hermeticshell case 12 can be cooled and respective sliding portions arepreferably lubricated, and the amount of oil sucked in the second rotarycompression element 34 via the refrigerant introduction pipe 92 becomesa preferable amount, the amount of oil enters the second rotarycompression element 34 and is discharged outside can be effectivelyreduced. As a result, the amount of oil entering the second rotarycompression element 34 is adjusted to a preferable amount, therebysolving or restraining adverse affect exerted upon the refrigerationcircuit while avoiding the lowering of the performance of the rotarycompressor 10 in advance.

Since the refrigerant introduction pipe 92 is provided such that a partof the inlet 92A of the refrigerant introduction pipe 92 is positionedunder the upper end of the stator 22 of the electric element 14, theheight dimension of the rotary compressor 10 can be reduced, therebyrestraining the height dimension of the rotary compressor 10substantially the same to that shown in the right side in FIG. 5compared with that of the conventional communication path 100 shown inthe left side in FIG. 5. As a result, the rotary compressor 10 is verysuitable for use in an automatic bending machine and a refrigeratorwhich is small in accommodation space and limited in size of thecompressor.

Meanwhile, according to the embodiment of the invention, the inventionis applied to the two stage compression type rotary compressor 10, theinvention is not limited thereto, but the invention is effective for themultistage compression type rotary compressor having more than twostages. Further, although the auxiliary discharge member 84 having theoil discharge port 84A is provided in the oil path 82 of the rotaryshaft 16 as the adjusting means, the oil adjusting means is not limitedthereto but the inner diameter of the oil discharge port 82A per seformed on the upper end of the rotary shaft 16 may be narrowed as theoil adjusting means.

The operation of the multistage_compression type rotary compressor shownin FIG. 6 is described next. The refrigerant discharged into thehermetic shell case 12 passes through the notch 22A and sucked in thesecond rotary compression element 34 through the inlet 92A of therefrigerant introduction pipe 92 in the same manner as that shown inFIG. 1. At this time, although a part of oil which is discharged throughthe intermediate discharge pipe 121 and not separated from therefrigerant and also a part of oil discharged through the oil dischargeport 84A of the auxiliary discharge member 84 provided at the upper endof the rotary shaft 16 as well as the refrigerant are sucked and flowinto the second rotary compression element 34 through the inlet 92A ofthe refrigerant introduction pipe 92, but the oil separation capacity inthe hermetic shell case 12 is improved compared with a case where theinlet 92A of the refrigerant introduction pipe 92 is opened to theinterior of the hermetic shell case 12 under the electric element 14.

Particularly, since the inner diameter of the oil discharge port 84A isset at the size such that the electric element 14 inside the hermeticshell case 12 can be cooled and respective sliding portions arepreferably lubricated, and the amount of oil sucked in the second rotarycompression element 34 via the refrigerant introduction pipe 92 becomesa preferable amount, the amount of oil entering the second rotarycompression element 34 and discharged outside can be effectivelyreduced. As a result, the amount of oil entering the second rotarycompression element 34 is adjusted to a preferable amount, therebysolving or restraining adverse affect exerted upon the refrigerationcircuit while avoiding the lowering of the performance of the rotarycompressor 10 in advance.

A rotary compressor 200 in which the inlet 92A of the refrigerantintroduction pipe 92 is opened to the upper end of the stator 22 isshown at the left side in FIG. 11, and the rotary compressor 10 of theinvention is shown in the right side in FIG. 11. As is evident from FIG.11, since the sleeve 144 for fixing the refrigerant introduction pipe 92is lowered to the height of the electric element 14 according to therotary compressor 10 of the invention, the height dimension of thecompressor is significantly reduced compared with that shown at the leftside in FIG. 11. As a result, the height dimension of the rotarycompressor 10 can be significantly reduced, and hence the rotarycompressor 10 is very suitable for use in an automatic bending machineand a refrigerator which is small in accommodation space and limited insize of the compressor.

The structure of the modified embodiment of the invention is shown inFIGS. 9 and 10. In this embodiment, a sleeve 144 is fixed to a shellcase body 12A corresponding to a plane portions 22C formed on the sidesurface of a stator 22, and an inlet 92A of a refrigerant introductionpipe 92 is opened to the interior of the plane portions 22C. That is,the plane portions 22C fulfill a role of a notch of the invention.Meanwhile, it is assumed that the width of each plane portions 22C isthe same as or slightly larger than the inlet 92A.

Even with such a structure, the height dimension of the rotarycompressor 10 can be reduced in the same manner as set forth above.However, since the refrigerant in the hermetic shell case 12 under theelectric element 14 can flow into the refrigerant introduction pipe 92,it is considered that the oil separation performance utilizing the spaceinside the hermetic shell case 12 is deteriorated in such a case thatthe refrigerant above the electric element 14 alone flows into therefrigerant introduction pipe 92. However, there is an advantage of thereduction of manufacturing cost of the stator 22, since it is notnecessary to provide a particular notch 22A as set forth.

The operation of the multistage compression type rotary compressor shownin FIG. 12 is described next. The intermediate pressure refrigerantsucked in the low pressure chamber of the upper cylinder 38 is subjectedto compressions of second stage by the operation of the roller 46 andthe vane (not shown) and is changed into high temperature and highpressure refrigerant, which in turn passes from the high pressurechamber through the discharge port, not shown, and also passes throughthe noise eliminating chamber 62 formed in the upper support member 54and the refrigerant discharge pipe 96 , then it is discharged outside,and flows into a gas cooler, not shown, in the same manner as that shownin FIG. 1.

What is sucked in the refrigerant introduction pipe 92 includes a partof oil which is discharged through the intermediate discharge pipe 121and not separated from the refrigerant and also a part of oil dischargedthrough the oil discharge port 84A of the auxiliary discharge member 84provided at the upper end of the rotary shaft 16 as well as therefrigerant. The invention is structured such that the amount ofdischarge of oil is adjusted by changing the size of the oil dischargeport 84A of the auxiliary discharge member 84.

The table 1 shows the inner diameter of the oil discharge port 84A, theamount of oil to be sucked in the second rotary compression element 34and lubricating characteristics of the second rotary compression element34 (the amount of oil at the second stage and lubricatingcharacteristics at the second stage). TABLE 1 Amount of lubri- oil atthe cating second character- Specification stage istics TestingDischarge of intermediate 15%  ◯ Specification pressure refrigerant(under the electric element) Blocked off oil path: None TestingDischarge of intermediate  10˜15%     ◯ Specification pressurerefrigerant (under {circle around (1)} the electric element) Blocked offoil path: None Testing Discharge of intermediate 7˜10%    ◯Specification pressure refrigerant (under {circle around (2)} theelectric element) Blocked off oil path: 4 mm diameter hole TestingDischarge of intermediate 5% ◯ Specification pressure refrigerant (under{circle around (3)} the electric element) Blocked off oil path: 2 mmdiameter hole Testing Discharge of intermediate 2% Δ Specificationpressure refrigerant (under {circle around (4)} the electric element)Blocked off oil path: 1 mm diameter hole

The amount of oil at the second stage in Table 1 shows an amount of oilwhich flows outside the hermetic shell case 12, is a ratio of the amountof circulation of oil in the refrigeration circuit and the amount ofcirculation refrigerant in the refrigeration circuit adding to theamount of circulation of oil. The test is performed under the samecondition in respect of the amount of oil from the oil pumped up fromthe reservoir 58, oil viscosity, environment temperature, the capacityof rotary compressor 10, the number of revolutions of the electricelement 14.

The column of the Testing Specification in this table shows cases wherethe intermediate pressure refrigerant in the hermetic shell case 12 isdischarged under the electric element 14, and it is discharge from thespace under the electric element 14 in the refrigerant introduction pipe92 (the oil path 82 is not blocked off by the auxiliary discharge member84), and the amount of oil in the second stage is large to the extent of15%, which exhibits excellent lubricating characteristics.

Testing Specification {circle around (1)} is the case, as shown in FIG.13 where the intermediate pressure refrigerant is discharged under theelectric element 14 of the hermetic shell case 12, and it is dischargedfrom the space over the electric element 14 into the refrigerantintroduction pipe 92, and the oil path 82 is not blocked off by theauxiliary discharge member 84. In this case, the amount of oil in thesecond stage is relatively large to the extent of 10 to 15%, whichexhibits excellent lubricating characteristics.

Testing Specification {circle around (2)} is the case where theintermediate pressure refrigerant is discharged under the electricelement 14 of the hermetic shell case 12, and it is discharged from thespace over the electric element 14 into the refrigerant introductionpipe 92, and the oil discharge port 82A provided at the upper end of theoil path 82 is blocked off by the auxiliary discharge member 84, and theoil discharge port 84A of the auxiliary discharge member 84 is set atinner diameter of 4 mm. In this case, the amount of oil at the secondstage is relatively small to the extent of 7 to 10%, which exhibitsexcellent lubricating characteristics.

Testing Specification {circle around (3)} is the case where theintermediate pressure refrigerant is discharged under the electricelement 14 of the hermetic shell case 12, and it is discharged from thespace over the electric element 14 into the refrigerant introductionpipe 92, and the oil discharge port 82A of the oil path 82 is blockedoff by the auxiliary discharge member 84, and the oil discharge port 84Aof the auxiliary discharge member 84 is set at inner diameter of 2 mm.In this case, the amount of oil at the second stage is small to theextent of 5%, which exhibits excellent lubricating characteristics.

Testing Specification {circle around (4)} is the case where theintermediate pressure refrigerant is discharged under the electricelement 14 of the hermetic shell case 12, and it is discharged from thespace over the electric element 14 into the refrigerant introductionpipe 92, and the oil discharge port 82A of the oil path 82 is blockedoff by the auxiliary discharge member 84, and the oil discharge port 84Aof the auxiliary discharge member 84 is set at inner diameter of 1 mm.In this case, the amount of oil in the second stage is significantlyreduced to the extent of 2%, which exhibits not excellent lubricatingcharacteristics.

It is found from the above results of the test that the circulation ofoil in the second rotary compression element 34 can be secured while theamount of oil which flows out to the refrigeration circuit is reduced inthe case where the inner diameter of the oil discharge port 84A of theauxiliary discharge member 84 is not less than 1.5 mm diameter and notmore than 3 mm diameter. Accordingly, the oil discharge port 84A havingthe inner diameter of 2 mm of the Testing Specification {circle around(3)} wherein the amount of oil is small to the extent of 5% withexcellent lubricating characteristics is employed by this embodiment.

That is, since the auxiliary discharge member 84 of the TestingSpecification {circle around (3)} is provided in the oil discharge port82A on the upper end of the oil path 82 for adjusting the amount of oilto be discharged into the upper space of the hermetic shell case 12, theoil pumped up by an oil pump P from the oil reservoir 58 passes throughthe oil path 82 of the rotary shaft 16 and it is discharged through theoil discharge port 84A into the upper space of the hermetic shell case12 by a proper quantity. A part of the oil discharged into the hermeticshell case 12 flows downward toward the oil reservoir 58 while coolingand circulating the electric element 14 and the like, while the properquantity of remaining oil flows from the space over the electric element14 into the refrigerant introduction pipe 92, and the oil is sucked inthe upper cylinder 38 of the second rotary compression element 34.

The oil discharge port 84A formed in the auxiliary discharge member 84may be provided not only at one spot but also at plural spots. In thelatter case, it is needless to say that a sectional area of a pluralityof oil discharge ports in total is equal to the sectional area of theoil discharge port 84A of the present embodiment.

As explained above, the rotary compressor having no auxiliary dischargemember 84 (shown in FIG. 13) on the oil discharge port 82A positioned atthe upper end of the oil path 82 provided in the rotary shaft 16 so asto adjust the inner diameter of the oil discharge port 82A, the oil isdischarged into the interior of the hermetic shell case 12 through theoil discharge port 82A positioned at the upper end of the oil path 82(shown by black arrows), but the amount of oil discharged through theoil discharge port 82A is large, so that a large amount of oildischarged from the oil discharge port 82A is sucked into the interiorof the refrigerant introduction pipe 92.

This oil is discharged outside the hermetic shell case 12 after it iscompressed by the second rotary compression element 34, resulting in thedeterioration of lubricating and sealing performance of the rotarycompressor 10, thereby also affecting adversely in the refrigerationcircuit. However, since the auxiliary discharge member 84 having the oildischarge port 84A for adjusting the inner diameter of the oil dischargeport 82A is formed in the oil discharge port 82A of the oil path 82provided in the rotary shaft 16, and the amount of oil to be dischargedthrough the oil discharge port 84A is adjusted to a proper quality, theamount of oil sucked in the second rotary compression element 34 throughthe refrigerant introduction pipe 92 can be set at an optimum value.

Accordingly, lubrication in the second rotary compression element 34 canbe optimized while reducing the amount of oil discharged outside fromthe second rotary compression element 34.

According to this embodiment, although the invention is applied to twostage compression type rotary compressor, the invention is not limitedthereto but can be effectively applied to the multistage compressiontype rotary compressor having more than two stages. Further, althoughthe auxiliary discharge member 84 having the oil discharge port 84A isprovided in the oil path 82 of the rotary shaft 16 as the adjustingmeans, the oil adjusting means is not limited thereto but is provided bynarrowing the inner diameter of the oil discharge port 82A per se formedat the upper end of the rotary shaft 16 as the adjusting means.

Still further, the operation of the multistage compression type rotarycompressor shown in FIG. 14 is described next. In the same manner as themultistage compression type rotary compressor shown in FIG. 1, oildischarged into the upper space over of the electric element 14 throughthe oil discharge port 82A provided at the upper end of the rotary shaft16 also moves upward toward in the hermetic shell case 12, and alsoflows downward into the oil reservoir 58 while cooling and lubricatingthe electric element 14, and a part of oil discharged into the upperspace over the electric element 14 through the oil discharge port 82Apasses through the refrigerant introduction pipe 92 and a suction path,not shown, formed in the upper support member 54, through the inlet 92A,then it is sucked in the low pressure chamber of the upper cylinder 38through the suction port, not shown, formed in the upper support member54.

Further, when the oil moves downward towards the hermetic shell case 12and flows downward into the oil reservoir 58, a foreign matter remainingin the hermetic shell case 12 is accumulated in the oil reservoir 58.Since the oil reserved in the oil reservoir 58 is pumped up by the oilpump P and discharged, the oil discharged through the oil discharge port82A on the upper end of the rotary shaft 16 is discharged together withthe foreign matter accumulating in the oil reservoir 58 through the oildischarge port 82A on the upper end of the rotary shaft 16.

Although a part of oil discharged through the oil discharge port 82A ora foreign matter mixed in the oil enters the refrigerant introductionpipe 92 through the inlet 92A, the foreign matter such as dust or a cutwaste which entered the refrigerant introduction pipe 92 through theinlet 92A is filtered by the filter 130 because the filter 130 isprovided in the inlet 92A of the refrigerant introduction pipe 92, andhence only both oil having no foreign matter therein and the refrigerantare sucked in the low pressure chamber of the upper cylinder 38 throughthe suction port.

The intermediate pressure refrigerant sucked in the low pressure chamberof the upper cylinder 38 is subjected to compression of second stage bythe operation of the upper roller 46 and the vane (not shown), and it ischanged into high temperature and high pressure refrigerant, which inturn passes from the high pressure chamber through the suction port, notshown, then also passes through the discharge noise eliminating chamber62 formed in the upper support member 54 and the refrigerant dischargepipe 96, and it is discharged outside, then it flows into a gas cooler,not shown, and the like.

The refrigerant in the gas cooler radiates heat, then it isdepressurized by a pressure reducing device, not shown, subsequently itflows into an evaporator, not shown. The refrigerant in the evaporatoris evaporated, then it passes through an accumulator and is sucked inthe first rotary compression element 32 through the refrigerantintroduction pipe 94, and this cycle is repeated.

Since the filter 130 is provided in the inlet 92A of the refrigerantintroduction pipe 92 through which the refrigerant is introduced, aforeign matter such as dust and a cut waste which remains in thehermetic shell case 12 can be filtered by the filter 130. Accordingly,it is possible to prevent the occurrence of abrasion and locking in therotary compression mechanism 18, thereby improving a reliability of therotary compressor 10.

Next, FIG. 15 shows a rotary compressor according to the thirdembodiment of the invention. In this embodiment, a filter 130 isprovided in a sleeve 141 at the side of an outlet 92C of a refrigerantintroduction pipe 92. The filter 130 is structured in the same manner asprevious embodiment, and it is mounted in the outlet 92C of therefrigerant introduction pipe 92 while being brought into contacttherewith in a state where an opening portion 130A is positioned at theupper stream side of the refrigerant and a tip end portion 130B ispositioned at the downstream side of the refrigerant. As a result, theforeign matter such as dust and cut waste which is produced when therotary compressor 10 is manufactured, and remains in the hermetic shellcase 12 can be caught and filtered by the filter 130 before it is suckedin the second rotary compression element 34 through the refrigerantintroduction pipe 92 in the same manner as the previous embodiments.Meanwhile, although the filter 130 is attached to the interior of thesleeve 144 in this example, it may be attached to the interior of theoutlet 92C of the refrigerant introduction pipe 92 (the outlet side ofthe refrigerant introduction pipe 92 in the foregoing both cases).

FIG. 16 shows an internal intermediate pressure multistage compressiontype rotary compressor according to the modified embodiment of theinvention. In the third embodiment, a strainer 131 (filtering means) isattached between an inlet 92A of a refrigerant introduction pipe 92 andan outlet 92C of the refrigerant introduction pipe 92. The strainer 131comprises a case 132 and a filter 130 attached to the interior of thecase 132 in the same manner as the previous embodiments. The filter 130is structured in the same manner as the previous embodiments wherein anopening portion 130A thereof is positioned at the upper stream side ofrefrigerant while a tip end portion 130B thereof is mounted in the case132 while brought into contact with the interior thereof in a statewhere it is positioned at the downstream side of the refrigerant. Withsuch a structure, since the filtering means is provided outside thehermetic shell case 12, assembling workability is improved. Even withsuch a structure, if a foreign matter such as dust and a cut waste,which is produced when manufacturing the rotary compressor 10 in thesame manner as the previous embodiments, and which remains in thehermetic shell case 12, enters the refrigerant introduction pipe 92, itcan be caught and filtered by the filter 130. In this third embodiment,since the case 132 is thicker than the refrigerant introduction pipe 92and the strainer 131 is provided in the case 132, the capacity forreceiving a foreign matter to be filtered by the filter 130 provided inthe inlet 92A of the inlet 92A of the refrigerant introduction pipe 92and the outlet 92C thereof.

Although the invention is applied to the two stage compression typerotary compressor but it is effectively applied to the multistagecompression type rotary compressor having more than two stages.

The operation of the internal intermediate pressure multistagecompression type rotary compressor in FIG. 17 according to the fourthembodiment is described next. The refrigerant sucked in the low pressurechamber of the upper cylinder 38 is compressed by the operation of theupper roller 46 and the vane, not shown, in the same manner as thatshown in FIG. 1, and it is changed into a high pressure (about 10 to 12MPaG) refrigerant, which in turn discharged from the high pressurechamber of the upper cylinder 38 into the discharge noise eliminatingchamber 62 through the discharge port, not shown. The refrigerantdischarged into the discharge noise eliminating chamber 62 is dischargedinto the hermetic shell case 12 under the electric element 14 throughthe discharge port 120, and passes through the stator 22 of the electricelement 14, the interior of the rotor 24, the distance therebetween andthe distance between the stator 22 and the hermetic shell case 12, thenit moves upward and finally reaches the space over the electric element14. At this time, most of oil mixed in the refrigerant is separated fromthe refrigerant in the hermetic shell case 12 and flows downward alongthe inner surface of the hermetic shell case 12, and is reserved in theoil reservoir 58 provided at the bottom of the hermetic shell case 12.Meanwhile, the refrigerant is discharged into the refrigeration circuitoutside the rotary compressor 10 through the refrigerant discharge pipe96 which is opened to the space over of the electric element 14.

Since the refrigerant compressed by the second rotary compressionelement 34 is discharged into the hermetic shell case 12 and the highpressure refrigerant in the hermetic shell case 12 is discharged outsidein such a manner, oil contained in the refrigerant discharged from thesecond rotary compression element 34 can be separated from therefrigerant in the hermetic shell case 12. Accordingly, the oilseparation performance is improved and the amount of oil which flows outto the refrigeration circuit provided outside the rotary compressor 10can be reduced, thereby restraining adverse affect exerted upon therefrigeration circuit. This is very advantageous in the case where theinvention is applied to a cooling system (car air conditioner and thelike) in which high pressure is reduced.

Further, since the interior of the hermetic shell case 12 becomes highpressure, the supply of oil to the first rotary compression element 32is effected by the difference in pressure, and oil discharged from thefirst rotary compression element 32 is directly supplied to the secondrotary compression element 34 together with the refrigerant, so that thesupply of oil to the second rotary compression element 34 is effectedwithout trouble.

Still further, oil is sufficiently contained the refrigerant which issucked in the second rotary compression element 34, the increase of thetemperature in the second rotary compression element 34 can be reduced.Accordingly, the increase of the temperature in the electric element 14under high compression operation can be also prevented. As a result, therotary compressor 10 having high performance and high reliability can beprovided.

Particularly, since the refrigerant introduction pipe 92 for introducingthe refrigerant discharged from the first rotary compression element 32into the second rotary compression element 34 through the outside of thehermetic shell case 12 is provided, the temperature of the refrigerantto be sucked in the second rotary compression element 34 can be reduced,thereby enhancing the improvement of the compression efficiency andreliability of the rotary compressor 10.

The operation of the internal intermediate pressure multistagecompression type rotary compressor of the fifth embodiment is describednext. Since the back pressure chamber 52A for applying a back pressureto the vane 52 shown in FIG. 17 and the discharge noise eliminatingchamber 64 of the first rotary compression element 32 are allowed tocommunicate with each other by the communication path 100, theintermediate pressure refrigerant which is compressed by the firstrotary compression element 32 is supplied to the back pressure chamber52A of the vane 52 of the first rotary compression element 32, which inturn urges the vane 52 against the lower roller 48.

Accordingly, the difference in pressure, i.e. between the pressure inthe lower cylinder 40 of the first rotary compression element 32 andthat in the back pressure chamber 52A, not shown, is reduced comparedwith a case where a high pressure is applied to the vane 52 of the firstrotary compression element 32 as the back pressure, and hence the loadapplied to the tip end of the vane 52 can be reduced. As a result, areliability of the rotary compressor 10 can be improved. Further, therefrigerant which leaks from the vane 52 of the first rotary compressionelement 32 to the interior of the lower cylinder 40 can be reduced, andhence it is possible to improve the compression efficiency.

Further, since the refrigerant compressed by the second rotarycompression element 34 is discharged into the hermetic shell case 12 andthe high pressure refrigerant in the hermetic shell case 12 isdischarged outside, oil contained in the refrigerant discharged from thesecond rotary compression element 34 can be separated from therefrigerant in the hermetic shell case 12. Accordingly, oil separationperformance is improved and the amount of oil flowing into the externalrefrigeration circuit outside the rotary compressor 10 can be reduced,thereby restraining adverse affect exerted upon an externalrefrigerating cycle. This is very advantageous in the case where theinvention is applied to a cooling system (car air conditioner and thelike) in which high pressure is reduced.

Still further, since the first and second rotary compression elements32, 34 are disposed under the electric element 14 and the first rotarycompression element 32 is disposed under the second rotary compressionelement 34, and also the refrigerant in the hermetic shell case 12 isdischarged outside from the space over the electric element 14, theseparation performance of oil from the high pressure refrigerant in thehermetic shell case 12 can be further improved. And also the structureof the invention is significantly effective in the case where carbondioxide, which becomes high in the difference in pressure, i.e. betweenhigh and low pressures, is used as the refrigerant.

Although the invention is applied to the vertical type rotary compressor10, the invention is not limited to the vertical type rotary compressoras set forth in the fourth, fifth and sixth embodiments of theinvention, and the invention is effectively applied to a so-calledlateral type multistage compression type rotary compressor in which theelectric element 14 and the rotary compression mechanism 18 are disposedin parallel with each other at the left and right in the oblong hermeticshell case 12.

Still further, the operation of the multistage compression type rotarycompressor shown in FIG. 18 is described next. The intermediate pressurerefrigerant in the hermetic shell case 12 passes through the refrigerantintroduction pipe 92 and also passes through the suction path, notshown, formed in the upper support member 54 and it is sucked in the lowpressure chamber of the upper cylinder 38 through the suction port 161in the same manner as that in FIG. 1. The thus sucked intermediatepressure refrigerant is subjected to compression of second stage by theupper roller 46 and the upper vane 50, and it is changed into the hightemperature high pressure refrigerant. Accordingly, the discharge valve127 provided in the discharge noise eliminating chamber 62 is opened sothat the discharge noise eliminating chamber 62 and the discharge port39 communicate with each other, and hence the refrigerant passes throughthe high pressure chamber of the upper cylinder 38 and discharge port39, then it is discharged into the discharge noise eliminating chamber62 formed in the upper support member 54.

Then, the high pressure refrigerant discharged into the discharge noiseeliminating chamber 62 flows into the gas cooler 154 through therefrigerant discharge pipe 96. At this time, since the temperature ofrefrigerant is increased up to substantially +100° C., and such hightemperature and high pressure refrigerant radiates heat through the gascooler 154, thereby heating water in a hot water storage tank, notshown, to produce hot water of about +90° C.

The refrigerant per se is cooled in the gas cooler 154 and it flows outfrom the gas cooler 154. Then, the refrigerant is depressurized by theexpansion valve 156, and then it enters the evaporator 157 where it isevaporated (at this time, heat is absorbed from the periphery), and itpasses through an accumulator, not shown, and it is sucked in the firstrotary compression element 32 through the refrigerant introduction pipe94, and this cycle is repeated.

In the case where the multistage compression type rotary compressor tobe used at a normal temperature is used at a cold district, the cylinderconstituting the second rotary compression element 34 is expandedoutward from the suction port 161 in the direction of rotation of theupper roller 46 to an extent of a predetermined angle to adjust an anglefor starting compression by the second rotary compression element 34, sothat the start of compression of the refrigerant in the upper cylinder38 of the second rotary compression element 34 is delayed, therebyreducing displacement of the second rotary compression element 34.

As a result, since the displacement of the second rotary compressionelement 34 can be set at an optimum value without changing thecomponents such as the upper cylinder 38 of the second rotarycompression element 34, the upper roller 46, the eccentric portion 42 ofthe rotary shaft 16, the cost caused by the change of the components canbe reduced.

Although the sixth embodiment is explained with reference to themultistage rotary compressor having the vertical type rotary shaft 16,it is needless to say that the invention can be applied to a multistagecompression type rotary compressor having a lateral type rotary shaft.

Still further, although the multistage compression type rotarycompressor of the embodiment is described with reference to the twostage compression type rotary compressor provided with the first andsecond rotary compression elements, the invention is not limitedthereto, and it is needless to say that the invention can be applied tothe multistage compression type rotary compressor provided with thethird, the fourth and more stage rotary compression elements.

As described in detail, since the internal intermediate pressuremultistage compression type rotary compressor comprising an electricelement in a hermetic shell case, and first and second rotarycompression elements being positioned under the electric element anddriven by a rotary shaft of the electric element, wherein refrigerantcompressed by said first rotary compression element is discharged intothe hermetic shell case, and the discharged intermediate pressurerefrigerant is compressed by said second rotary compression element,wherein it further comprises a refrigerant introduction pipe which isopened to the interior of the hermetic shell case over the electricelement and introduces the refrigerant in the hermetic shell case intothe second rotary compression element through an outside of the hermeticshell case, wherein a part of an inlet of the refrigerant introductionpipe is positioned under the upper end of a stator of the electricelement, the amount of oil which is sucked in the refrigerantintroduction pipe and is discharged outside from the second rotarycompression element can be reduced compared with a case where therefrigerant introduction pipe is opened to the space under the electricelement, so that the deterioration of lubricating and sealingperformance in the rotary compressor and the occurrence of an adverseaffect caused by the oil in the external refrigeration circuit can beeffectively solved. Further, the attachment position of the refrigerantintroduction pipe is lowered, the height dimension of the rotarycompressor is reduced, for example, thereby providing the rotarycompressor which is preferably adapted to an automatic vending machineand the refrigerator and the like which is small in accommodation spaceand limited in size of the rotary compressor.

1-15. (canceled)
 16. An internal intermediate pressure multistagecompression type rotary compressor comprising an electric element in ahermetic shell case, and first and second rotary compression elementsbeing driven by the electric element, wherein refrigerant which iscompressed by the first rotary compression element and discharged issucked in, compressed by and discharged into the second rotarycompression element: and wherein an upper cylinder constituting thesecond rotary compression element is expanded outward from a suctionport to an extent of a predetermined angle in a direction of rotation ofan upper roller.
 17. An internal intermediate pressure multistagecompression type rotary compressor comprising an electric element in ahermetic shell case, and first and second rotary compression elementsbeing driven by the electric element, wherein refrigerant which iscompressed by the first rotary compression element and discharged issucked in, compressed by and discharged into the second rotarycompression element; and wherein an upper cylinder constituting thesecond rotary compression element is expanded outward from a suctionport to an extent of a predetermined angle in a direction of rotation ofan upper roller from a suction port, and wherein a ratio of thedisplacement of the first rotary compression element relative to that ofthe second rotary compression element is set by adjusting an angle forstarting compression by the second rotary compression element.